I too was taught to counter pull as the fist goes in the other hand is withdrawn with equal power using the adding the shoujlder rotation to the rest of the body power. My teacher taught us to aim for a point approx 6" behind the target going right through the opposition. At the moment of impact every part of the body goes solid channeling the power into the target. By practicing the correct technique in the dojo. you develop power so when you need to hit in a real situation a less than perfect technique still hurts. i notice how in competition the blow is withdrawn at the moment of impact instead of driving through the target.